Oven for cooking foods

ABSTRACT

An oven ( 100 ) comprising an oven chamber ( 105 ) for the cooking of foods, heating means ( 125 ) for heating the oven chamber, and a vapor exhaust system ( 155 ) for treating vapors produced in the oven chamber during a food cooking process. The vapor exhaust system comprises: a first region ( 405 ) in fluid communication ( 160,165,170 ) with the oven chamber so as to receive vapors exiting the oven chamber and wherein the vapors are de-moisturized and cooled down; and a second region ( 410 ) downstream the first region and wherein the de-moisturized and cooled down vapors exiting the first region are mixed to hot dry air ( 140 ) before being exhausted to the outside ambient.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to cooking apparatuses for cooking orbaking foods, of the type having a cooking chamber, like cooking ovens,both for domestic and for professional use. Within this general scope,the present invention relates to improvements in respect of thetreatment of vapors produced in the cooking chamber while cooking food.In the rest of the description, with “cooking” it will be intended anykind of preparation of foods by heat, including baking.

2. Overview of the Relevant Known Art Related to the Invention

Cooking apparatuses comprise a cooking chamber in which food is cooked.During the cooking process, vapors forms in the cooking chamber of thecooking apparatus. Vapors are predominantly in the form of steam andconsist of water vapor for the most part; in addition, they also containoils and fats, which are present in the form of aerosols or else inliquid form. Other components may also be contained therein.

Vapors are created during the cooking process through the vaporizationof water that is naturally contained in the foods being cooked; inaddition, however, vapor that is deliberately fed into the cookingchamber of the apparatus (either by way of an external steam generatoror else by direct vaporization of water inside of the hot cookingchamber) for some types of cooking also contributes to the creation ofvapors. This water vapor is intentional and is important for certainaspects of the cooking process.

When fat-containing foods or fat-containing cooking products are cookedat high temperatures, the aforementioned oil and fat aerosols areadditionally created.

Vapors in excess must be exhausted to the outside, otherwise anundesired vapor pressure would build up within the cooking chamber. Someconventional cooking apparatuses have an exhaust air opening from whichsteam or vapors can escape into the room air, but this can lead to astrong accumulation of moisture and heat in the room air in thesurroundings of the cooking apparatus and in the entire kitchenpremises; moreover, the room is also dirtied by the oil and fat aerosolscontained in the escaped vapors. All this is totally unsatisfying.

US 2011/072983 discloses a cooking apparatus having a cooking chamber,wherein the vapors created in the cooking chamber are removed with avapor outlet channel. A vapor condensation device brings the vapors intocontact with a cooling liquid. The vapor condensation device has acontainer, in which a liquid bath is located. The vapor outlet channelcarries the vapors out of the cooking chamber into the container of thevapor condensation device. There, the vapors are brought into contactwith the liquid from the liquid bath and thereby partially condensed.Furthermore, a device drain is provided. The container of the vaporcondensation device has a vapor guide element, that guides the vaporsthrough one or more channels in the container; the vapor guide elementis configured such that one wall of the wall surfaces of the channel orchannels is formed by the surface of the liquid bath in the container.

EP 691513 discloses an oven having a cooking interior enclosed by a doorand casing. There is a heater and floor drain removing condensate. Abovethe oven, an extraction hood removes water vapor, via a fan. Preferably,a suction duct connects the extraction hood to drain. A hood intake isimmediately above the door opening and leads to a condenser integralwith the hood; this has vertical baffle surfaces defining a steamchannel. The base surfaces slant toward the extraction duct connection.

SUMMARY OF THE INVENTION

The Applicant has tackled the problem of devising a solution forproviding an oven with an improved treatment of vapors produced in thecooking chamber while cooking or baking food.

According to an aspect of the present invention, there is provided anoven comprising an oven chamber for the cooking of foods, heating meansfor heating the oven chamber, and a vapor exhaust system for treatingvapors produced in the oven chamber during a food cooking process.

The vapor exhaust system comprises:

a first region in fluid communication with the oven chamber so as toreceive vapors exiting the oven chamber and wherein the vapors arede-moisturized and cooled down; and

a second region downstream the first region and wherein thede-moisturized and cooled down vapors exiting the first region are mixedto hot dry air before being exhausted to the outside ambient.

Therefore, the oven has, associated with the first region, means forde-moisturize and cool down vapors received from the oven chamber, and,associated with the second region, means for mixing hot dry air to thevapors exiting the first region.

Preferably, said first region extends vertically.

Advantageously, in the first region a tortuous path for the vapors isformed.

Said tortuous path may be a duct comprising a plurality of baffles.

In an embodiment, at least one of said baffles is hollow and is runthrough a heat-exchange fluid.

Advantageously, a coolant liquid feeding device may be associated withsaid first region, arranged for feeding a coolant liquid into the firstregion for cooling down the vapors.

Said coolant liquid feeding device may comprise at least one liquidfeeding nozzle adapted to spray coolant liquid into said first region ina nebulized form.

Said coolant liquid feeding device may for example be arranged to causethe coolant liquid to enter into the first region proximate to a topside thereof.

Said coolant liquid feeding device is preferably connected to anactivator adapted to selectively activate said coolant liquid feedingdevice for selectively feeding the coolant liquid.

Preferably, at least a temperature sensor is associated with the firstregion, arranged for sensing the temperature of the vapors entering intothe vapors exhaust system.

Said coolant liquid feeding device may be selectively activated based ona sensed temperature of the vapors sensed by said temperature sensor.

The oven may comprise at least an air propeller associated with saidvapor exhaust system and configured for promoting the exit of vaporsfrom the oven chamber and their flow through the vapor exhaust system.

Said air propeller may comprise an axial or radial fan arranged at theexit of the second region.

Said air propeller may be selectively activatable.

Advantageously, said hot dry air comprises air exploited to cool down atleast one among a door of the oven and/or air exploited to cool downinternal oven parts subjected to heat up during the oven operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of exemplary and non-limitativeembodiments of the present invention will help to render the above aswell as other features and advantages of the present invention clearer.For its better intelligibility, the following description should be readwhile referring to the attached drawings, wherein:

FIG. 1 schematically shows an oven according to an embodiment of thepresent invention, in cross-section according to a vertical planeorthogonal to a front of the oven;

FIG. 2 schematically shows the oven of FIG. 1 in cross section accordingto a plane parallel to the front of the oven, indicated in FIG. 1 asII-II;

FIG. 3 schematically shows the oven of FIG. 1 and FIG. 2 in crosssection according to a horizontal plane, indicated in FIG. 2 as III-III;

FIG. 4 is a schematization of a vapor exhaust tower of the oven of FIG.1 to FIG. 3, with indicated different vapor control regions;

FIG. 5 is a schematization similar to FIG. 4, with notations used in amathematical analysis of the different vapor control regions;

FIG. 6 is a simplified Carrier diagram or psychrometric chart (specifichumidity in ordinate versus temperature in abscissa), of the humid airfor a first control region of the vapor exhaust tower;

FIG. 7 is a complete Carrier diagram of the humid air for a firstcontrol region of the vapor exhaust tower;

FIG. 8 is a complete Carrier diagram of the humid air for a secondcontrol region of the vapor exhaust tower;

FIG. 9 is a schematic flowchart of an exemplary way of operation of theoven according to an embodiment of the present invention, and

FIG. 10 shows, in a schematical view similar to that of FIG. 5, a vaporexhaust tower according to another embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

Referring to FIG. 1, FIG. 2 and FIG. 3, an oven according to anembodiment of the present invention is schematically depicted, in threecross-sectional views (as explained in the Brief description of thedrawings).

The oven, denoted as a whole 100, comprises an oven chamber 105 (cookingchamber) wherein the foods to be cooked/backed are to be introduced forbeing cooked.

The oven chamber 105 is a delimited region of space within an ovencabinet 110 having a front opening 115 for inserting/removing the foods,which is selectively closable by an oven door 120, hinged to the ovencabinet 110 so as to be movable by an oven user between a closedposition (the one depicted in FIG. 1) adapted to close the front opening115, and an open position (not depicted in the drawings) in which theoven chamber 105 is accessible through the front opening 115.

Inside the oven chamber 105, heating elements 125, for example one ormore resistive heaters, are provided, energizable for heating up theoven chamber environment.

Preferably, an air propeller 130 is also provided inside the ovenchamber 105, operable (possibly in a selective way, depending on a foodcooking program selected by the oven user) to cause air circulationwithin the oven chamber 105 so as to better distribute the air heated upby the heating elements 125 and achieve a more uniform temperatureinside the oven chamber 105.

It is pointed out that although in FIG. 1 the heating elements 125 aredepicted as arranged at the periphery of the air propeller 130, this ismerely an example; the heating elements might be arranged in differentlocations, and/or additional heating elements might be arranged indifferent locations of the oven chamber 105, e.g. at the top and/or atthe bottom thereof.

The oven door 120 is designed so to have an air gap 135 formed therein,for the passage of cooling air 140 having the function of cooling theexternal panel 145 (usually of glass or other transparent material) ofthe oven door 120, in order to keep such external panel at a temperaturesufficiently low not to be harmful for the oven user. The oven doorcooling air 140 is for example taken in from the outside ambient, e.g.through an opening formed at the bottom of the door 120.

In a space formed between the oven chamber 105 and the walls of the ovencabinet 110, thermally-insulating material 150 is preferably provided,in order to avoid heat dissipation from inside the oven chamber 105 tothe outside ambient, and at the same time reducing the temperature ofthe cabinet walls when the oven 100 is operating.

Albeit not shown, it is intended that the oven 100 may comprise severalother components, like for example a steam and/or microwavesgenerator(s) to be supplied to the oven chamber 105 for performing someparticular kinds of cooking processes.

According to the present invention, the oven 100 is equipped with asystem for exhausting vapors that are produced within the oven chamber105 when foods are cooked. Advantageously, the vapor exhaust system isintegrated, embedded in the structure of the oven 100.

In the exemplary embodiment of the present invention here presented, thevapor exhaust system comprises a vapor exhaust tower 155 which isaccommodated at the rear of the oven 100, e.g. approximately at thecenter or more or less proximate to a corner of the oven cabinet 110,like the rear-left corner (looking the oven 100 frontally), as shown inthe drawings (it is intended that the position of the vapor exhausttower 155 is not at all limitative for the present invention).

The vapor exhaust tower 155 according to an embodiment of the presentinvention will be hereafter described with the help of the principleschematic of FIG. 4.

The concept at the basis of the vapor exhaust tower 155 according to thepresent invention is the (selective) superposition of three physicalphenomena: a de-humidification, de-hydration, moisture condensation ofthe vapors coming from the oven chamber 105 (phenomenon A); a cooling ofthe vapors (phenomenon B), and an adiabatic intermixing of the vaporswith relatively hot and dry air (phenomenon C).

In an embodiment of the present invention, phenomena A and B may takeplace concurrently, as depicted in the schema of FIG. 4, in a bottomsection 405 of the exhaust tower 155; phenomenon C takes place in a topsection 410 of the exhaust tower 155.

Referring back to FIG. 1 and FIG. 2, the exhaust tower 155 is, at abottom thereof (i.e., at a bottom of the bottom section 405), fluidlyconnected to a vapor discharge duct 160 that, having an inlet 165preferably at the bottom of the oven chamber 105 (e.g., approximately inthe central position), runs, preferably declining, towards an outlet 170opening approximately at the bottom of the exhaust tower bottom section405.

The bottom of the exhaust tower bottom section 405 is also fluidlyconnected to a liquid drainage 175 (only part of which is shown), which,when the oven is installed in a kitchen, is connected to a kitchen waterdrainage spigot.

In the exhaust tower bottom section 405, a tortuous, sinuous,serpentine, labyrinthic path is formed, for example, as in the exampledepicted in the drawings, by means of properly offset baffles 177.

In a vertical position along the exhaust tower bottom section 405,vertical position that in the shown embodiment is approximately at thetop of the exhaust tower bottom section 405, an inlet 415 for a coolingliquid is advantageously present, which for example may comprise anozzle for spraying cooling water that is selectively fed, for exampleunder control of a valve 420, e.g. an electrovalve, controlled by anoven control unit (shown only schematically in FIG. 4 and denoted 423).The nozzle preferably is adapted to spray water in a nebulized form,i.e. as very small droplets. The cooling water is for example fed via apiping that, when the oven is installed, is coupled to a water outletspigot of the kitchen.

Preferably, a temperature sensor 425 may be provided in a verticalposition along the exhaust tower bottom section 405, for exampleapproximately at the bottom of the exhaust tower bottom section 405,proximate to the outlet of the vapor discharge duct 160. When present,the temperature sensor 425 is in signal connection with the oven controlunit 423 to communicate thereto the readings about the temperature ofthe vapors exiting the oven chamber 105. The oven control unit 423 mayfor example be programmed so as to activate the electrovalve 420 whenthe temperature of the vapors exiting the oven chamber 105 (and enteringthe vapor exhaust tower 155) reaches a pre-set temperature, which mayalso depend on the specific cooking programme selected by the oven user.

At a top thereof, the exhaust tower bottom section 405 has an opening430 leading into the exhaust tower top section 410, which is for examplemore or less vertically aligned to the underlying bottom section 405.The exhaust tower top section 410 has one or more inlets for relativelyhot and dry air, which is introduced so as to be intermixed to thede-moisturized vapor that, after exiting the oven chamber 105, haspassed through the exhaust tower bottom section 405. The exhaust towertop section 410 may include a first hot air inlet 433, in the shownexample located more or less midway the exhaust tower top section 410,for admitting hot air that has been taken in from the outside ambientfor cooling oven parts like the motor for the air propeller 130, amongwhich there may be the exhaust tower bottom section 405, and a secondhot air inlet 435, in the shown example located more or less at the topof the exhaust tower top section 410, for admitting the oven doorcooling air 140, that, after passing in the gap 135 formed in the ovendoor 120, passes in a gap between the oven chamber 105 and a top panelof the oven cabinet 110.

A fan 180 is advantageously provided at the top of the exhaust tower topsection 410. The fan 180, that preferably is selectively activatable bythe oven control unit 423, creates a depression inside the exhaust tower155 and sucks the vapor and the cooling fluxes inside it. Downstream thefan 180, i.e. on top of it, the exhaust tower 155 opens into theexternal ambient or into a discharge duct.

For the sake of explanation of its principle of operation, the systemfor exhausting vapor according to an embodiment of the present inventioncan advantageously be regarded as made up by two so-called “controlregions”. A first control region is the exhaust tower bottom section405, where the phenomena A and B take place. A second control region isthe exhaust tower top section 410, where the phenomenon C takes place.

In the first control region 405, the labyrinthic path formed by thebaffles 177 allows compactizing the vapor exhaust tower 155, therebyreducing its space occupation.

When the electrovalve 420 is open and the nozzle 415 sprays coolingwater, thanks to the presence of the baffles 177 a sort ofwaterfall-type filter is formed, that at each fall condenses the vaporsexiting the oven chamber 105 and filters them by retaining the particlesof fat transported by the vapors.

The baffles 177 allows the cooling water, sprayed by the nozzle 415, tohave more time and surface area available for enhancing heat exchangebetween the sprayed cooling water and the vapors coming from the ovenchamber 105. In addition, the presence of the baffles 177 enables thesprayed cooling water to release at least part of the heat absorbed bythe vapors to the baffles 177 and the walls of the vapor exhaust tower155 (this heat can then be dispersed outside the vapor exhaust tower155, and may advantageously contribute to heating up the air that isthen introduced into the exhaust tower top section 410 through the firstair inlet 433). Concurrently, the injected cooling water cools down thebaffles 177, on which the moisture contained in the vapors cancondensate.

The injection of the cooling water by the nozzle 415 in the form ofnebulized droplets, creates a sort of fog inside the first controlregion 405, that contributes to the increase of the thermal exchangearea and at the same time reduces the power and resources (water)consumption and the generated noise.

In the second control region 410, the heat released by the vaporspassing through the first control region (exhaust tower bottom section)405 as well as by the operation of the oven (e.g., the motor of the airpropeller 130) is caused to be absorbed by the cooling air (that entersinto the vapor exhaust tower 155 through the first hot air inlet 433),thereby increasing the temperature thereof. This allows to reduce therelative humidity of the cooling air (at constant specific humidity),thereby increasing the capacity of the cooling air of absorbing theresidual humidity of the vapors exiting the first control region 405,when they are mixed with the cooling air: in fact, by increasing thetemperature of the cooling air, the specific humidity of the flow ofintermixed vapors and cooling air remains substantially the same, whilethe relative humidity decreases; the capability of absorbing thehumidity contained in the flow of vapors is thus increased.

FIG. 5 schematizes again the vapor exhaust system according to anembodiment of the present invention, and should be referred to as an aidfor the following analytical analysis of the energy and mass balance.Hereafter, for the purpose of notation, it is assumed that the normal tothe control regions is directed as exiting the surface delimiting thecontrol regions. The mechanical work is regarded as positive if exitingthe control regions (i.e., when directed as the normal to the controlregions) whereas the heat is regarded as positive if entering into thecontrol regions (i.e., when opposite to the normal). The energy and massflows are regarded as positive if directed as the normal to the controlregions.

The vapor exhaust system according to an embodiment of the presentinvention can be regarded as comprised of three “control volumes” or“control regions”: the first and second control regions 405 and 410introduced in the foregoing, and a third control region made up by theunion of the first and second control regions 405 and 410.

For the purpose of notation, hereinafter the terms {dot over (m)} denotemass flow rates of dry air; the subscript “steam” denotes the flowscontaining a certain amount of vapor. In any case, the term in is to beintended as referred to the fraction of dry air present in a flow,whereas the fraction of humid air present in a flow is denoted as {dotover (m)}·x, with x denoting the specific humidity. The terms withsubscript “engine” or “door” refer to the flux of cooling air of theengine of the air propeller 130 (entering into the vapor exhaust tower155 through the inlet opening 433) and, respectively, of the flux 140 ofthe cooling air of the oven door (entering into the vapor exhaust tower155 through the opening 435).

Let:

-   -   r₀ be the water vaporization heat (water vaporization enthalpy),        and    -   c_(p), c_(v) constants.

Then:

${x = \frac{m_{vapour}}{m_{air}}},{{\varphi = \frac{m_{vapour}}{m_{saturation}}};}$

where x denotes the specific humidity and φ denotes the relativehumidity,and where the mass flows rates {dot over (m)}_(steam) and {dot over(m)}_(steam2) of dry air entering and exiting the first control region405 (equal to each other, since as mentioned above the mass flow ratesare referred to the fraction of dry air) are defined as {dot over(m)}_(a):

{dot over (m)} _(a) ={dot over (m)} _(steam) ={dot over (m)} _(steam2)

The energy and mass balance equations for the first control region 405are:

Q ₁ ⁻ ={dot over (m)} _(a)(h _(steam2) −h _(steam))+{dot over (m)}_(H2O) _(out) h _(H2O) _(out) −{dot over (m)} _(H2O) h _(H2O)  Eq. (1)

{dot over (m)} _(H2O) _(out) ={dot over (m)} _(H2O) +{dot over (m)}_(a)(x _(steam) −x _(steam2))  Eq. (2)

where the first equation (Eq. (1)) relates to energy (the suffix “-” forthe heat Q₁ means that the heat exits the control region; the symbols hdenote the enthalpy), and the second equation (Eq. (2)) relates to themass of water. The term (x_(steam)−x_(steam2)) is due to thecondensation of moisture.

In order to solve the first equation Eq. (1) for the energy, let FIG. 6be considered, showing a simplified Carrier diagram for humid air. Thetransformation “1→2” marked on the diagram can be decomposed into thetwo transformations “1→3” (latent contribution) and “3→2” (sensiblecontribution).

Considering that:

$\begin{matrix}{{\overset{.}{m}\left( {h_{2} - h_{1}} \right)} = {\overset{.}{m}\left\lbrack {{{\left( \frac{\partial h}{\partial t} \right)_{x} \cdot \Delta}\; t} + {{\left( \frac{\partial h}{\partial x} \right)_{t} \cdot \Delta}\; x}} \right\rbrack}} & {{Eq}.\mspace{14mu} (3)}\end{matrix}$h=h _(a) +x·h _(v)  Eq. (4)

where h_(a) denotes the enthalpy of a dry air flow and h_(v) denotes theenthalpy of a flow of humid air, being:

h _(a) =c _(pa) ·t

h _(v) =r ₀ +c _(pv) ·t

it follows that Eq. (4) becomes:

h=c _(pa) ·t+x·(r ₀ +c _(pv) ·t)  Eq. (5)

and then, by derivation of Eq. (5):

$\left( \frac{\partial h}{\partial t} \right)_{x} = {{c_{pa} + {x \cdot {c_{pv}\left( \frac{\partial h}{\partial x} \right)}_{t}}} = {r_{0} + {c_{pv} \cdot t}}}$

The energy balance equation (Eq. (1)) can thus be developed as:

Q ₁ ⁻ ={dot over (m)} _(a)(c _(pa) +x _(steam2) ·c _(pv))(t _(steam2) −t_(steam))+{dot over (m)} _(a)(r ₀ +c _(pv) ·t _(steam))(x _(steam2) −x_(steam))+{dot over (m)} _(H2O) _(out) h _(H2O) _(out) −{dot over (m)}_(H2O) h _(H2O)  Eq. (6)

By defining:

$\begin{matrix}{c_{pu}\overset{\bigtriangleup}{=}{\left( \frac{\partial h}{\partial t} \right)_{x} = {c_{pa} + {x \cdot c_{pv}}}}} & {{Eq}.\mspace{14mu} (7)}\end{matrix}{and}$ $\begin{matrix}{h_{v}\overset{\bigtriangleup}{=}{r_{0} + {c_{pv} \cdot t}}} & {{Eq}.\mspace{14mu} (8)}\end{matrix}$

the following developments are possible (introducing Eq, (2), Eq. (7)and Eq. (8) in Eq. (6)):

Q ₁ ⁻ ={dot over (m)} _(a) c _(pu)(t _(steam2) −t _(steam))+{dot over(m)} _(a) h _(v)(x _(steam2) −x _(steam))+{dot over (m)} _(H2O)(h _(H2O)_(out) −h _(H2O))+{dot over (m)} _(a) h _(H2O) _(out) (x _(steam) −x_(steam2))

Q ₁ ⁻ ={dot over (m)} _(a) Δh _(sensible) +{dot over (m)} _(a) Δh_(latent) +{dot over (m)} _(H2O)(h _(H2O) _(out) −h _(H2O))+{dot over(m)} _(a) h _(H2O) _(out) (x _(steam) −x _(steam2))

Q ₁ ⁻ =Q _(s) ⁻ +Q _(λ) ⁻ +{dot over (m)} _(H2O)(h _(H2O) _(out) −h_(H2O))+{dot over (m)} _(a) h _(H2O) _(out) (x _(steam) −x_(steam2))  Eq. (9)

where:

Q₁ ⁻ is the heat flow at the walls;

Q_(s) ⁻, Q_(λ) ⁻ are the fractions of sensible and latent energies ofthe flow of humid air;

{dot over (m)}H2O(h_(H2O) _(out) −h_(H2O)) is the Energy fraction of theliquid;

{dot over (m)}_(a)h_(H2O) _(out) (x_(steam)−x_(steam2)) is the Energyfraction of the condensed water.

FIG. 7 depicts the complete Carrier diagram of the humid air for thefirst control region 405. The point on the diagram indicated as 1corresponds to the state of the flow of vapors upon entering into thefirst control region; the point indicated as 2 corresponds to the stateof the flow of vapors upon exiting the first control region. As can beappreciated looking at the diagram, the state of the flow of vaporsexiting the first control region is rather close to the state indicatedas s on the diagram, corresponding to the saturation condition (withrelative humidity φ equal to 100%): thus, by spraying cooling water intothe first control region, the temperature of the vapors decreases, andthe relative humidity φ increases, but the specific humidity x decreases(because the flow of vapors exiting the first control region has a lowercontent of humidity).

Coming to the second control region 410, FIG. 8 depicts the respectivehumid air Carrier diagram. The point 2 on the diagram represents thestarting state of the flow of vapors upon entering into the secondcontrol region (it corresponds to the point 2 on the Carrier diagram ofFIG. 7).

The balance equations are:

$\begin{matrix}{{{{\overset{.}{m}}_{door}h_{door}} + {{\overset{.}{m}}_{engine}h_{engine}} + {{\overset{.}{m}}_{{steam}\; 2}h_{{steam}\; 2}}} = {{{\overset{.}{m}}_{final}h_{final}}=={\left( {{\overset{.}{m}}_{door} + {\overset{.}{m}}_{engine} + {\overset{.}{m}}_{{steam}\; 2}} \right)h_{final}}}} & {{Eq}.\mspace{14mu} (10)} \\{{{{\overset{.}{m}}_{door}x_{door}} + {{\overset{.}{m}}_{engine}x_{engine}} + {{\overset{.}{m}}_{{steam}\; 2}x_{{steam}\; 2}}} = {{{\overset{.}{m}}_{final}x_{final}}=={\left( {{\overset{.}{m}}_{door} + {\overset{.}{m}}_{engine} + {\overset{.}{m}}_{{steam}\; 2}} \right)x_{final}}}} & {{Eq}.\mspace{14mu} (11)}\end{matrix}$

where Eq. (10) is the energy balance equation and Eq. (11) is the massbalance equation.

Dividing the two equations above for {dot over (m)}_(final) it follows:

$h_{final} = {{\frac{{\overset{.}{m}}_{door}}{{\overset{.}{m}}_{final}}h_{door}} + {\frac{{\overset{.}{m}}_{engine}}{{\overset{.}{m}}_{final}}h_{engine}} + {\frac{{\overset{.}{m}}_{{steam}\; 2}}{{\overset{.}{m}}_{final}}h_{{steam}\; 2}}}$$x_{final} = {{\frac{{\overset{.}{m}}_{door}}{{\overset{.}{m}}_{final}}x_{door}} + {\frac{{\overset{.}{m}}_{engine}}{{\overset{.}{m}}_{final}}x_{engine}} + {\frac{{\overset{.}{m}}_{{steam}\; 2}}{{\overset{.}{m}}_{final}}x_{{steam}\; 2}}}$

The state of the flow of vapors, in the second control region, movesfrom point 2 to point 4, which represents the state of the flow ofvapors exiting the second control region. Points 5 and 6 represent thestates of the flows of hot and dry air entering into the second controlregion and that are mixed with the flow of vapors: both arecharacterized by a low relative humidity φ).

The third control region is the union of the first and second controlregions 405 and 410. The energy and mass balance for the third controlregion can thus be obtained from the above equations. The result is thatthe variables related to the common surfaces to the first and secondcontrol regions are eliminated, i.e. {dot over (m)}_(steam2)h_(steam2),and {dot over (m)}_(steam2)x_(steam2) ({dot over (m)}_(steam2)={dot over(m)}_(a)).

At the end, the flow of vapors exiting the second control region has arelatively low content of humidity.

FIG. 9 is a simplified flowchart illustrating a possible way ofoperation of the oven 100 according to an embodiment of the presentinvention.

When the oven 100 is started, the oven control unit 423 reads theoperation selected by the oven user (block 905). The oven control unit423 then decides whether or not the oven user has selected and started acooking operation (decision block 910). If the oven user has not decidedto start a cooking operation (exit branch N of decision block 910), theoperation flow jumps back to block 905. If instead the oven user hasselected and started a cooking operation (exit branch Y of decisionblock 910), the oven control unit 423 obtains information about the typeof cooking selected by the oven user (block 915).

Then, depending on the type of cooking selected by the oven user, theoven control unit 423 decides whether or not the air propeller 180 is tobe activated (block 920). If yes, the air propeller 180 is activated, ifnot, the air propeller 180 is kept off.

Still based on the type of cooking selected by the oven user, the ovencontrol unit 423 determines (block 921) at which pre-set temperature ofthe vapors entering the vapor exhaust tower 155, the electrovalve 420 isto be activated to enable the intake of cooling water; suchdetermination made by the control unit 423 may be carried out exploitinga database of parameters database, from which the oven control units 423picks at which pre-set temperature of the vapors entering the vaporexhaust tower 155. Then, by exploiting the readings of the temperaturesensor 425, the oven control unit 423 monitors the temperature of thevapors leaving the oven chamber 105 (block 923). In particular, the ovencontrol unit 423 checks if such temperature is over the pre-setintervention temperature (block 925).

Until the temperature of the vapors leaving the oven chamber 105 andentering into the vapor exhaust tower 155 remains below the pre-setintervention temperature (exit branch N of decision block 925), the ovencontrol unit 423 checks whether the cooking process is terminated(decision block 930): if the oven control unit 423 determines that thecooking process is terminated (exit branch Y of decision block 930), theoven control unit 423 checks (decision block 931) if the electrovalve420 is currently open: in the affirmative case (exit branch Y ofdecision block 931) the electrovalve 420 is closed (block 933); afterclosing the electrovalve 420 (or leaving it closed, if it was alreadyclosed—exit branch N of decision block 931), the oven control unit 423checks (decision block 935) whether the fan 180 is running in theaffirmative case (exit branch Y of decision block 935), the fan 180 isleft running for a predetermined time after the end of the cookingprocess, whereas if the fan 180 is not running (exit branch N ofdecision block 935) the oven control unit 423 activates the fan 180(block 940) for a predetermined time. The operation flow then jumps backto block 905. If the oven control unit 423 determines that the cookingprocess has not terminated yet (exit branch N of decision block 930),the oven control unit 423 checks whether the electrovalve 420 isactivated (decision block 943): in the negative case (exit branch N ofdecision block 943), the operation flow returns to block 923, where theoven control unit 423 obtains a new reading of the temperature sensor425; if instead the oven control unit 423 assesses that the electrovalve420 is activated (exit branch Y of decision block 943), the oven controlunit 423 de-activates the electrovalve 420 (block 945) and then theoperation flow returns to block 923.

Let now be supposed that the temperature of the vapors leaving the ovenchamber exceeds the pre-set temperature (decision block 925, exit branchY): the oven control unit 423 activates the electrovalve 420 (block950); cooling water thus starts to be sprayed by the nozzle 415 into theexhaust tower bottom section 405, to cool the vapors exiting the ovenchamber 105.

The oven control unit 423 then determines whether the cooking processhas terminated (decision block 955): if not (exit branch N of decisionblock 955), the operation flow jumps back to block 923 (where the ovencontrol unit 423 obtains a new reading of the temperature sensor 425; ifinstead the oven control unit 423 determines that the cooking processhas terminated (exit branch Y of decision block 955), the oven controlunit 423 obtains (through the temperature sensor 425) the temperature ofthe vapors entering into the vapor exhaust tower 155 (block 960), andthen the oven control unit 423 checks whether the temperature of thevapors exceeds the pre-set intervention temperature (decision block965): until the vapors temperature stays above the pre-set interventiontemperature (exit branch Y of decision block 965), the electrovalve 420is kept open, and the oven control unit 423 continues to monitor thevapor temperature. When the vapor temperature falls below the pre-setintervention temperature (exit branch N of decision block 965) theelectrovalve 420 is closed (block 933) and the same operations describedabove (blocks 935 and 940) are performed. The operation flow returns toblock 905.

In other words, the injection of cooling water into the exhaust towerbottom section 405 (i.e., into the first control region of the vaporexhaust system) is selectively enabled based on an assessment of thetemperature of the vapors that leaves the oven chamber 105 and entersinto the vapor exhaust tower. Also the activation of the fan 180 isselective, depending on the cooking process.

The vapor exhaust system according to the described embodiment of thepresent invention comprises a sinuous, tortuous, labyrinthic vaporsconduit arranged vertically, into which cooling water can (selectively)be injected. The tortuous shape of the conduit, thanks to the depressiongenerated by a fan downstream the first control region (in the shownexample, the fan 180) allows exploiting the inertia of the particles ofvapor/fat, pushing them against the baffles 177 (in particular, againstthe first ones, proximate to the bottom of the exhaust tower bottomsection 405). The spray of nebulized cooling water allows capturing thefinest particulate (and this effect is also promoted by the baffles 177proximate to the top of the exhaust tower bottom section 405, which arecooled down by the water spray).

Experimental trials carried out by the Applicant have shown that thetemperature of the vapor flow exiting the vapor exhaust system accordingto the described embodiment of the present invention, also in criticaloperating conditions (oven chamber temperature set to 250° C. and 100%of humidity), did not exceed 30° C. at a relative humidity of 25% (with19° C. of ambient air temperature).

In FIG. 10 there is depicted, schematically as in FIG. 4, a vaporexhaust tower according to a slightly different embodiment of thepresent invention; components, parts and elements that are identical,similar or equivalent to those described in connection with the previousembodiment are denoted with same reference numerals. A difference of theembodiment of FIG. 10 compared to the previous embodiment resides inthat at least part (one, more than one, possibly all) of the baffles177, like the baffles 1077 visible in the figure, are hollow at theirinterior and arranged to be run through by a relatively coldheat-exchange fluid 1005 (e.g., liquid, like water), which receives heatreleased from the vapors passing through the first control volume 405.In this way, the heat released by the vapors leaving the oven chambercan be at least partly collected by the heat-exchange fluid, instead ofbeing only dissipated.

Another difference in the embodiment of FIG. 10 compared to the previousembodiment is the different position of the nozzle 415 (which in thisembodiment is not at the top of the first control region) and of thetemperature sensor 425 (which in this embodiment is not at the bottom ofthe first control region). In particular, differently from the previousembodiment, in this embodiment the nozzle 415 is associated to a lowerportion of the bottom section 405 with respect to the temperature sensor425.

In FIG. 10 just one opening in the exhaust tower top section 410 isshown; this single opening may schematize the two openings 433 and 435of the previous embodiment, but it might also be possible that throughsuch single opening both of the two cooling air fluxes enter into thevapor exhaust tower. In still other embodiments, one of the two coolingair fluxes might be absent.

Also with the vapor exhaust tower of the embodiment of FIG. 10, the oven100 may operate as described in connection with the previous embodiment(flowchart of FIG. 9).

In the foregoing, exemplary embodiments of the present invention havebeen presented and described in detail. Several modifications to thedescribed embodiments, as well as alternative ways of practicing theinvention are conceivable, without departing from the protection scopedefined by the appended claims.

1. An oven (100) comprising an oven chamber (105) for the cooking offoods, heating means (125) for heating the oven chamber, and a vaporexhaust system (155) for treating vapors produced in the oven chamberduring a food cooking process, characterized in that the vapor exhaustsystem comprises: a first region (405) in fluid communication(160,165,170) with the oven chamber so as to receive vapors exiting theoven chamber and wherein the vapors are de-moisturized and cooled down;and a second region (410) downstream the first region and wherein thede-moisturized and cooled down vapors exiting the first region are mixedto hot dry air (140) before being exhausted to the outside ambient. 2.The oven of claim 1, wherein said first region extends vertically. 3.The oven of claim 1, wherein in the first region a tortuous path for thevapors is formed.
 4. The oven of claim 3, wherein said tortuous path isa duct comprising a plurality of baffles (177;1077).
 5. The oven ofclaim 4, wherein at least one of said baffles is hollow and run througha heat-exchange fluid (1005).
 6. The oven of claim 3, wherein a coolantliquid feeding device (415,420) is associated with said first region,arranged for feeding a coolant liquid into the first region for coolingdown the vapors.
 7. The oven of claim 6, wherein said coolant liquidfeeding device comprises at least one liquid feeding nozzle (415)adapted to spray coolant liquid into said first region in a nebulizedform.
 8. The oven of claim 6, wherein said coolant liquid feeding deviceis arranged to cause the coolant liquid to enter into the first regionproximate to a top side thereof.
 9. The oven of claim 6, wherein saidcoolant liquid feeding device is connected to an activator adapted toselectively activate said coolant liquid feeding device for selectivelyfeeding the coolant liquid.
 10. The oven of claim 6, wherein at least atemperature sensor (425) is associated with the first region, arrangedfor sensing the temperature of the vapors entering into the vaporsexhaust system.
 11. The oven of claim 10, wherein said coolant liquidfeeding device is selectively activated based on a sensed temperature ofthe vapors sensed by said temperature sensor.
 12. The oven of claim 1,comprising at least an air propeller (180) associated with said vaporexhaust system and configured for promoting the exit of vapors from theoven chamber and their flow through the vapor exhaust system.
 13. Theoven of claim 12, wherein said air propeller comprises an axial orradial fan arranged at the exit of the second region.
 14. The oven ofclaim 12, wherein said air propeller is selectively activatable.
 15. Theoven of claim 1, wherein said hot dry air comprises air exploited tocool down at least one among a door (120) of the oven and/or airexploited to cool down internal oven parts subjected to heat up duringthe oven operation.